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Elpasolite scintillators such as Cs₂LiYCl₆:Ce (CLYC) and Cs₂LiLaBr₆₋ₓClₓ:Ce (CLLBC) combine gamma-ray spectroscopy with intrinsic neutron sensitivity through the ⁶Li(n,t)αreaction, making them attractive for compact measurements in mixed radiation fields. This work compares the measured response of 1-inch × 1-inch CLYC and CLLBC detectors coupled to silicon photomultipliers with a Geant4 detector-response model for an AmBe neutron source.
Experimental light-output spectra were calibrated using ¹³⁷Cs and ¹⁵²Eu gamma-ray measurements and are reported in MeV electron equivalent (MeVee). The AmBe assembly incorporates a moderated source container and a radial measurement port. A removable polyethylene plug provides two operating configurations: with the plug installed, neutrons are moderated to produce a thermal-enhanced field; with the plug removed, the resulting air-filled channel provides increased exposure to fast neutrons. The simulation samples the AmBe neutron spectrum and its associated 4.439 MeV gamma-ray emission, transports particles through the source–moderator–detector system, applies particle-dependent conversion from deposited energy to scintillation light output, and includes detector-resolution broadening derived from calibration data.
The characteristic quenched ⁶Li-capture features were fitted using a Gaussian peak with a linear background. For CLYC, the measured and simulated centroids were 3.0196 ± 0.0016 and 3.0253 ± 0.0023 MeVee, respectively, corresponding to a difference of 5.7 keV. For CLLBC, the respective centroids were 2.81394 ± 0.00035 and 2.81050 ± 0.00068 MeVee, differing by 3.4 keV. These statistical agreements support the light-output treatment of the alpha–triton capture products. Differences remain in peak width, peak area and the low-energy continuum, where detector packaging, room scattering, electronics response and the full engineering geometry are not yet completely represented.
The combined experimental and modelling approach provides a basis for separating source, moderation and detector-material effects. Ongoing work will implement variance reduction for the engineering geometry, improve calibration and quenching systematics, and extend the comparison to absolute neutron-response measurements in the thermal-enhanced and fast-neutron configurations.